1. Field of the Invention
The present invention relates to a color converting apparatus for use in a proof generating system for generating a color proof carrying a color image on a proof sheet for examining colors and making color corrections, with a proofer which is an image outputting device such as a color printer or the like before a colored printed material with a color image printed on a print sheet is produced by a color printing machine such as a rotary press.
2. Description of the Related Art
It has heretofore been customary in the art of printing and platemaking to generate a color proof carrying a color image on a proof sheet for examining colors and making color corrections, with a proofer such as a color printer or the like before a colored printed material with a color image printed on a print sheet is produced as a final finished product by a color printing machine such as a rotary press.
The proofer is used because it does not require films and printing plates that would be needed by printing machines and can easily generate as many hard copies carrying color images on proof sheets, i.e., color proofs, as required at a low cost within a short period of time.
To form a color image for use as a color proof on a proof sheet, image data dependent on devices such as a printer, a photographic camera, an image sensor, a CRT, an LED, etc., e.g., C (Cyan), M (Magenta), Y (Yellow), B (Black) image data, are converted to calorimetric data that are device-independent image data, i.e., X, Y, Z (stimulus) image data by a standard printing profile such as a four-dimensional lookup table (LUT) or the like that are provided by the manufacturer. Then, a color proof carrying a color image on a proof sheet is produced by a proofer such as a color printer according to a proof profile, e.g., a printer profile (three-dimensional lookup table).
The color proof thus produced by the proofer such as a color printer simulates the colors of a colored printed material to be produced by a color printing machine for confirming the colors prior to an actual printing process carried out by the color printing machine.
In order to generate a color proof with a proofer which is an image outputting device, as described above, it is necessary to convert device-dependent image data to device-independent image data with a printing condition profile as a printing condition color converting means, and then to convert the device-independent image data to device-dependent image data with a printer condition profile as an output condition color converting means and input the device-dependent image data to the image outputting device.
Heretofore, it has been the practice to perform separate computerized processing operations to effect a color conversion process with the printing condition color converting means and a color conversion process with the output condition color converting means. Therefore, these color conversion processes have been time-consuming.
The inventors have decided that the color conversion processes are time-consuming primarily because two processing procedures are required, i.e., input image data are converted to output image data by the printing condition color converting means, and thereafter the output image data are supplied as input image data to the output condition color converting means, which converts the supplied input image data to desired output image data.
Another reason for the time-consuming color conversion processes is that a highly specialized professional skill is needed to perform the computerized processing operations.